Mechanical calculator



(No Model.) 2l Sheets--Sheet 1.

, R. DUNCAN. MBGHANIGAL CALCULATOR. No. 591,332. Patented Oct. 5,1897.

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2 Sheets-Sheet 2.

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R. DUNCAN. MECHANICAL CALCULATOR.

No. 591,332. Patented OCt. 5,1897.

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UNITED STATES PATENT OEEicE.

`ROBERT DUNCAN, QF KNOXVILLE, TENNESSEE.

M ECHANICAL CALCULATOR.

SPECIFICATION forming part of Letters Patent No. 591,332, dated October 5, 1897. Application filed February 8,1897. Serial No. 622,532. (No model.)

To all whom it may concern.'

Be it known that I, ROBERT DUNCAN, of Knoxville, in the county of Knox and State of Tennessee, have invented a new and Improved Mechanical Calculator, of which the following is a full, clear, and exact description.

This invention relates more particularly to devices for computing the charge to be made for a guest at a hotel; and the object is to provide a simple device by means of which the hotel clerk can quickly ascertain the amount of a guests bill without resorting` to mental iiguring.

The invention comprises a rotary calendar and cost-price disk and a rotary rate-disk.

The invention further consists in the construction and novel arrangement of parts, as will be hereinafter fully set forth, and pointed out in the claims.

Reference is to be had to the accompanying drawings, forming a part of this specification, in which similar characters of reference indicate corresponding parts in all the views.

Figure 1 is a front view of a device embodying my invention. Fig. v2 is a section on the line 2 2 of Fig. 1. device of modified construction. Fig. 4 is a rear view thereof, and Fig. 5 is a section through the line 5 5 of Fig. 4.

Referring first to the example of my invention shown in Figs. l and 2, l and 2 indicate the front and rear walls of a casing separated at the edge by a strip 3. Arranged to rotate between the front and rear walls 1 and 2 of the casing is a disk 4, having a calendar or iigures 5 arranged around its periphery on its upper surface, and designed to indicate the date of the days of a month. The top wall 1 of the casing is provided with openings 6, through which the several figures may be seen.

Arranged on the disk 4 within the circle of figures 5 are several circular rows of figures 7 for indicating the number of days, and within these several rows of figures indicating the number of days are several other rows of figures 8, indicating the amount of a bill. The several igures of each row 7 and 8 are divided by radial lines, printed or otherwise marked on the disk 4.

Mounted to rotate on the upper wall l of the casing is a rate-disk 9. The rate-disk 9 Fig. Bis a front view of a Valso the letters S and L may be rotated independently of the disk 4, and as a means for rotating the disk 4 I pro- .vide a finger-piece 10, which has a hub-like portion extended through a central opening in the disk 9 and having an angular portion engaging in a correspondingly-shaped opening inthe disk 4. Therefore it will be seen that by rotating the finger-piece 10 the disk 4 may be rotated and that the disk may be rotated on the finger-piece.

The rate-disk 9 is provided with a peripheral opening 1l, through which the several sets of the gures 7 may be seen, and inside of this opening 1l the said disk 9 is provided with a keystone-shaped opening 12, through which several sets of the iigures 8 may be seen. At one side of the opening 12 the rate in dollars and fractional marks are printed on the disk 9, and at the opposite side of said opening l2 is a series of marks indicating the cost for fractional parts of days.

At one side of the opening 11 are printed the letters 15, D, S, L, and below the said opening are also printed the letters 13, D, S, L. The first-named letters are arranged with the B in line with the outer line of figures 7. The next letter, D, is arranged in line with the next line of iigures 7. The letter S is arranged in line with another inner set of circumferentiallyarranged iigures 7, and the letter L is arranged in line with the inside set of circumferentially-arrang'ed iigures. In the second series of letters the letter B is arranged to be moved into coincidence with one radial line of gures 7, the letter D coincident with another radial line of figures 7, and so are These letters are intended to indicate the quarters of a day-that is, the letter will indicate breakfast-time, the letter D indicating dinner-time, the letter S supper-time, and the letter L lodging-time.

In operation the guest when entering the hotel registers at one of the four divisions of the daythat is, should he arrive at breakfast-time and partake of the same his bill will date from that time. Whenleaving, he is booked up to the last meal or lodging. To

ascertain the amount of the bill, the clerk will set the disk 4 so that the calendar-date upon which the guest arrived will be opposite the IOO star 4or other indicator 13, and then he will move the rate-disk around to the right until the opening 11 is coincident with the date upon which the guest leaves. IIe then takes the number of days as shown on the circle of figures 7 coincident with the letter indicating the time of day of his arrival, and then he observes the ligure in said line which is in the radial line of the letter indicating the time of day of departure, and then by refer- .ring to the rate-disk the amount of the bill is quickly ascertained. For example, a guest registers on the fifth day of the month at dinner and leaves on the tenth day of the month at supper time. The fifth day of the calendar is set opposite the pointer 13, and then the rate-wheel is moved around to bring its opening 11 opposite 10 of the calendar. Following the circumferential line D toits joining with the radial line S it will be seen that live and one-half days are registered. Referring to the rate-column 14.- at three dollars and fifty cents per day and following the curved line therefrom to a point coincident with the radial line from the figure 5, printed on the disk 4L inside the several rows of cost-figures, it will be seen that $17.50 is indicated-thatiis, this $517.50 gives the price for :five days of board at three dollars and fifty cents per day; but as there is still onehalf a day to be added the circular line opposite the $23.50 is to be followed to the column showing fractional parts of the day and in the space marke( 9,4, where $1.75 will be found. This, added to $17. 50, makes $19.25, the total amount of the bill.

In the example of my improvement shown in Figs. 3, 1, and 5 I have designed the device as a weekly calendar, operating, however, on the same principle as the one first described. In this example the disk 15 has the days of a week printed around its edge, and the letters thereof may be seen through openings 16 in the front wall 17 of the casin g. This front wall 17 has printed upon it a series of spaced circular lines and a series of spaced radial lines. In the spaces formed by the intersecting circular and radial lines are printed figures 1S, indicating the number of days. Mounted to rotate on the front wall 17 is a disk 19, having an opening 20 in its edge, near one side edge of which are printed the letters 13, 13, S, L, and adjacent to the lower edge of which are printed the letters D, 1), S, L These letters are for the same purpose and operate in the same manner as the letters before described.

Mounted to rotate with the disk 10, but on the opposite side of the disk 15, is a segmental disk 21. These two disks 19 and 21 are each connected to the head portion of a shaft 22, mounted to rotate in a hole formed in the central portion of the front wall 17 ofthe casing, and the disk 15 is mounted to rotate on this shaft. The disk 15 is made in the form of a wheel-that is, it has a rim upon which the days of the week are printed-and it has radial spokes, on the Vrear side of which are printed figures indicating the price per day, and upon the disk 21 is printed a series of figures representing the price for fractions of a day, such as one-fourth, one-hall", and three-fourths of a day. One of the openings 16 in the front wall 17 of the casing is somewhat elongated, as shown at 2S, and the rim portion of the disk 15 is provided with depressions or holes into which the point of.' a pencil or similar device may be inserted to rotate said diskthat is, by inserting a pencil in the depression or hole at one end of the slot 23 the disk should be rotated until the pencil strikes against the other end of the slot, and this will give a proper length of movement to the disk to bring the letters in dicating the several days of the week into the sight-openings.

In the operation of this device the disk l5 will be rotated to bring the date of arrival of a guest opposite the pointer As here shown, Tuesday is indicated. Assuming that the guest has arrived at breakfast-time on Tuesday and departs at supper-time on XVednesday, the opening' 2O of the disk lll will be turned opposite the letters indicating IVednesdav Following the circular row of figures coincident with the letter I3 to the space in radial line with the let ter S it will be seen that one and three-fourths days are indicated. Assuming the price per day to be live dollars, the clerk by reversing the instrument will note that the outer line of figures in line with the space marked 1 indicates $5.00, this being in line with the figures indicating $55.00 on the adjacent spoke of the disk 15; but as this only gives the price for one day the price for three-:fourths of a day will be found at the outer edge of the last column of figures printed on the disk 21,whieh indicates $53. 75. This, added to the 235. o() before ascertain ed, gives $58. 75, the amount of the bill for one and three-fourths days.

The calendar-table on the device shown in Fig. 1 indicates thirty-one days, because there are more months in a year composed of thirtyone days than of any other number. In cal culating the time 'in a month of less than thirty-one days, where a guest registers in one month and leaves in the following month, the calendar-disk is advanced the number of days the month is short of thirty-one. For instance, a guest registers on the 28th of J une and leaves on the 2d of July, the calendar would be set to the 29th instead of the 28th. This applies only where a guest arrives in one month and departs in the following month and only in months having less than thirty-one days.

"While I have described my device as particularly adapted for hotel purposes, it is obvious that it may be used as a computing scale for other purposcs-sucln for instance, as ascertaining the amount due a workmanand obviously by slight changes in the sys- ITO tem of lettering and figuring it might be employed as an interest table or computer.

Having thus described my invention, l claim as new and desire to secure by Letters Patentl. A mechanical calculator, comprising a rotary calendar-disk, the said calendar-disk having iigures indicating the numbers of days and also a series of gures indicating total amounts, and another disk mounted to rotate relatively to the first-named disk and having an opening in its edge to disclose figures indicating the number of days, and having letters printed on one side of said opening indicating fractions of a day and also having letters at the lower edge of said opening indicating the fractions of a day, a series of iigures indicating day-rates printed at one side of another opening in said last-named disk, and a series of gures printed at the opposite side of said last-named opening indicating the cost-price for fractions of a day, substantially as speciied. l

2. A mechanical calculator, comprising a casing having a circular row of slot-openings through its front Wall, a disk mounted to rotate in said casing and having day-dates printed near its periphery to be disclosed through said slot-openings, the said disk also having a series of annular roWs of figures indicating numbers of days and also having a series of annular rows `of igures indicating total amounts, and another disk mounted to rotate relatively to the rst-named disk and having an opening in its edge, on the inner and one side edge of which are printed the letters B, D, S, L, the said other disk being also provided with a keystone-shaped opening adjacent to one edge of Which is printed a series of figures indicating the rate of cost per day, and having printed adjacent to the other side of said opening a series of figures indicating the cost for fractions of a day, substantially as specified.

3. A mechanical calculator, comprising a casing, a Wheel-shaped disk having day-indieating marks near its edge, designed to be disclosed through openings in the casing, radial spokes on said disk having per-day cost-marks, a series of iigures on the casing indicating total amounts, a series of figures on said casing indicating total numbers of days, and a disk having an opening in its edge through which day-indicating figures may be seen, one of said openings being longer than the other so that an instrument may be moved along it While engaged with the disk for rotating it, substantially as specified.

ROBERT DUNCAN.

Witnesses:

Louis DUNCAN, WILLIAM B. DUNCAN. 

